Then the sixth angel poured his bowl on the great river Euphrates. Its water was dried up so that the way was ready for the kings from the east.
Then I saw three unclean spirits, like frogs, come from the dragon's mouth, the beast's mouth, and the mouth of the false prophet.
These are demonic spirits that do signs. They go out to the kings of the whole world, to gather them for battle on the great day of God the Almighty. (
Look! I'm coming like a thief! Favored are those who stay awake and clothed so that they don't go around naked and exposed to shame.)
The spirits gathered them at the place that is called in Hebrew, Harmagedon.
References for Revelation 16:16